Establishment of a cell-based assay to screen insulin-like hypoglycemic drugs.

This study sought to establish a cell based assay to screen insulin analogs. Previous studies have proposed that up-regulation of glucose consumption may have the same anti-diabetic effects as insulin. Here, the amount of glucose that disappeared in culture medium after incubation with insulin or drugs was determined and served as an indicator of the glucose consumption of the cells. In order to establish a cellular model to screen insulin analogs, the sensitivities of four cell lines - BALB/c 3T3, HepG2, NIH3T3, and Bel7402 - to insulin were evaluated by detecting glucose consumption after incubation with insulin (0-125 nM) for 24 h. BALB/c 3T3 was more sensitive to insulin than the other three cell lines. Insulin elevated glucose consumption of BALB/c 3T3 in a concentrationand time- manner. Glucose consumption of BALB/c 3T3 increased by 30% after incubation with insulin (30 nM) for 24 h. Insulin increased the proliferation of BALB/c 3T3 at 48 h. A model was established by detecting glucose consumption after treating BALB/c 3T3 with drugs for 24 h. Using the cell-based assay, we screened more than two thousand samples from Traditional Chinese Medicine (TCM). Five extracts exhibiting glucose absorbance in medium were identified, indicating a hit rate of 0.5%. Results suggested that a cell-based assay by detection of glucose consumption in BALB/c 3T3 was suitable for high-throughput screening and was feasible to identify insulin-like hypoglycemic drugs. Five hits were discovered from natural products. Further characterization of these active extracts could help to identify potential anti-diabetic drugs.